Located in the high Andes, Ubinas has been threatening a major eruption since the summer of 2013, when the volcano shot an ash plume into the air – something that had not occurred since 2010. At first experts thought the ash plumes were purely phreatic (i.e. steam-drive eruptions caused by hot magma’s effect on ground water, such as increased snowfall at the crater) rather than related to a new flow of magma rising. By September, however, it became evident that magma was rising indeed rising, and the activity began to intensify.

By March of 2014 a fresh lava dome had appeared at Ubinas, and renewed explosive activity, with ash clouds rising to 4,000 meters (13,000 feet) were followed by smaller explosions and increasing tremors. The increasing activity, as well as the health risks from the irritating ash emissions prompted evacuations of villagers as well as their livestock (mostly alpaca and llamas) in mid-April.

The strongest explosions occurred on April 19, when large lava bombs were ejected up to 2.7 km (1.7 mi) away. After this, there was a period of strong ash venting and degassing, which was described as likely the result of clearing a conduit. Fresh lava was reported at Ubinas in mid to late April as well, again suggesting that an obstruction had been cleared.

On May 1, 2014 the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Aqua satellite passed over Ubinas just as it was expelling a large ash plume. Ubinas is located in the center of the image and is seen as a light ash-gray circle with dark gray on the southeast quadrant. A medium-gray plume rises almost straight up from the volcano. It has a billowing appearance, with darker shadows and lighter, more reflective areas, suggesting it is in motion and is quite thick. The plume also casts a long, dark shadow on the northeast side of the volcano.

Although this image captures a dramatic moment, the plume is not as high as many in recent months, and may represent a quieter phase of the eruptive cycle. According to Volcano Discovery, since about the second half of April, visual and seismic activity at the volcano have been decreasing, and explosions and emissions have almost ceased – although some of both are still occurring. This may indicate a quieting of Ubinas, at least for the time being.

Ubinas is Peru’s most active volcano, with intermittent mild to moderate eruptions recorded in history since 1550.